Many techniques exist for measuring resistance in a fuel cell, such as the current interrupt method, the AC resistance method, the high frequency resistance (HFR) method and the electrochemical impedance spectroscopy (EIS) method. The objective of each method is to determine the resistance of the fuel cell.
The current interrupt method is a time-domain AC technique requiring a quick interrupt of the fuel cell current and measuring the terminal voltage before and after the interruption. The AC resistance method requires the application of a fixed, single high frequency wave (sine) to the fuel cell in order to measure the total impedance magnitude of the fuel cell. In the HFR method, the electrolyte resistance is determined using the real component of the impedance measured at high frequency. The EIS technique is similar to the HFR method, but involves applying the AC perturbation over a broad range of frequencies and monitoring the variations in magnitude and phase of the voltage and current.
While there are several methods available for measuring resistance in a fuel cell, there exists a need for improved methods of measuring resistance in a fuel cell. Surprisingly, the present invention meets this and other needs.